Question

OC and OR are similar. Find the length of QP.

Answer 1

Given:

Circle C and circle R are similar.

The length of arc AB is $s = \frac{22 \pi}{9}$

The radius of circle C (AC) = 4 unit

The radius of circle R (QR) =6 unit

To find the length of arc QP.

Formula

The relation between s,  r and $\theta$ is

$arclength = 2\pi r \frac{\theta}{360}$

where,

s be the length of the arc

r be the radius

$\theta$ be the angle.

Now,

For circle C

Taking r = 4

According to the problem,

$2 \pi r \frac{\theta}{360} = \frac{22 \pi}{9}$

or, $2r \frac{\theta}{360} = \frac{22}{9}$ [ eliminating $\theta$ from both side]

or, $\theta = \frac{(22)(360)}{(9)(2)(4)}$

or, $\theta = 110^\circ$

Again,

For circle R

Taking, r = 6 and $\theta = 110^\circ$ we get,

The length of arc QP is

$arc length = 2\pi (6)(\frac{110}{360} )$

or, $arclength = \frac{11 \pi}{3}$

Hence,

The length of QP is $\frac{11 \pi}{3}$. Option C.